Shocks, struts and other damping devices are used in shock absorbing systems to dissipate vibrational and other forces. In vehicle shock absorbing systems, such damping devices are used to absorb shock loads sustained by the wheel assemblies of such vehicles and are used in combination with coil springs. Damping devices typically operate by transmitting the applied forces to a rod and piston combination slidably mounted in a fluid-filled chamber of an inner tube of the damper. As the piston is urged through the chamber, the fluid in the chamber is forced through and around the piston. The resistance of the piston to movement through the fluid in the chamber is directly proportional to the applied force. In this manner the movement of the rod and piston, and thereby the applied forces, are damped.
Strut or shock type dampers may include a rod guide assembly that guides and centers the rod and piston as they reciprocate within the inner tube. When lateral or "side load" forces are applied to the damper, the rod and piston may be shifted away from the radial center of the damper. Furthermore, deviations in tolerances in the various components of the damper can also shift the rod and piston off center. Radial misalignment of the rod and piston within the damper causes the rod to rub against the rod guide as it reciprocates within the inner tube, which increases wear on the rod and rod guide. This is especially undesirable in dampers containing magnetorheological fluid, the suspended magnetic particles of which can be abrasive to the rod. Furthermore, when the rod is laterally displaced, the rod can engage and laterally displace the rod guide, which in turn shifts the inner tube from the radial center of the damper. The shift in position of the inner tube increases wear upon various bearings, seals, and sleeve supports in the damper.
In order to prevent undue wear to a damper piston rod, some struts are provided with an outer tube bearing a bracket adjacent its lower end for attachment to a vehicle wheel suspension assembly and which is closed at its lower end by a strut base. One end of the piston rod is fixed to the middle of the strut base, and the rod projects upward into an inner tube containing the piston and fluid. The top of the inner tube is fixed to the vehicle body, so that the rod and piston thus move axially together with the outer tube and wheel assembly in opposition to the inner tube and vehicle body. Side loads applied to the strut are received by bearing elements between the inner and outer tubes; and very little of these side loads are thus applied to the rod. But apparatus must be provided to close and seal the bottom of the inner tube against loss of working fluid; and this assembly must accommodate the stroking action of the rod therethrough. This apparatus includes a rod guide and seal assembly, which, although relieved of most of its side loads, still includes a bearing and seal in contact with the rod. The rod guide and seal assembly thus provides a third point of radial support for the rod between the point of attachment to the strut base at the bottom and the piston at the top. If manufacturing tolerances or other factors cause the rod guide to be laterally misaligned with these other supports, it may cause undesirable wear between itself and the rod. Accordingly, there is a need for a rod guide and seal assembly that can accommodate manufacturing tolerances in lateral alignment with other rod support apparatus while providing secure sealing around an axially moving rod to maintain the working fluid within the working chambers of the damper.